1. Field of the Invention
This invention relates to a foldable stroller frame, more particularly to an improved foldable stroller which is convenient to use and which occupies a relatively small space when folded.
2. Description of the Related Art
The improvement of this invention is directed to the foldable stroller frame of a conventional stroller shown in FIG. 1. As illustrated, the conventional stroller includes an inverted U-shaped handle 11 with two arms, a pair of front wheel support rods 12 each of which has an upper end portion and a lower end portion connected to a front wheel 17, and a pair of rear wheel support rods 13 each of which has an upper end portion connected to the upper end portion of the front wheel support rod 12, and a lower end portion connected to a rear wheel 18. Each of the arms of the handle 11 is slidable relative to a respective one of the front wheel support rods 12 between a first position, wherein the conventional stroller frame is unfolded, and a second position, wherein the conventional stroller frame is folded. The stroller frame includes a seat supporting device 14 consisting of a pair of horizontal connecting rods 141 each of which connects a respective one of the front wheel support rods 12 to a respective one of the rear wheel support rods 13, a pair of L-shaped seat supporting members 14 for supporting a seat 16 thereon, and a pair of sliding blocks 144 mounted slidably on the connecting rods 141 respectively. The seat 16 is provided with four positioning pins 161, 162 (only two are shown) which are respectively engaged within the positioning notches 143 of the connecting rods 141. A lock device 2 is pivoted to the upper end portion of a respective one of the front wheel support rods 12 and the upper end portion of a respective one of the rear wheel support rods 13, and has a through hole, through which one of the arms of the handle 11 passes slidably in a position parallel to the front wheel supporting rod 12. The arms of the handle 11 and the front wheel support rods 12 can slide within the lock devices 2 and two sleeves 15. A locking mechanism is provided on a respective one of the lock devices 2 so as to lock the arm of the handle 11 against movement relative to the front wheel support rod 12 when the arm of the handle 11 is placed in the first position.
When it is desired to fold the stroller frame for storage, each of the lock devices 2 is operated in order to permit the arm of the handle 11 to slide downward so as to be juxtaposed to the front wheel support rods 12, and the rear wheel support rods 13 are pressed toward the front wheel support rods 12 to be juxtaposed to the front wheel support rods 12 such that the rear wheels 18 are disposed on the front wheels 17. As shown in FIG. 4, since the front wheel support rods 12, the rear wheel support rods 13, and the arms of the handle 11 are juxtaposed to each other, and since both the front and rear wheels 17, 18 are disposed adjacent to the lower end portions of the front wheel support rods 12, the folded stroller frame occupies a relatively large space. It is inconvenient and inexpensive to store and transport the conventional stroller frame. Another drawback of the conventional stroller frame is that the lock devices 2 have a complicated structure such that the lock device is difficult and inconvenient to operate. In particular, as shown in FIGS. 2 and 3, the lock device 2 includes a lock body 21, a coiled compression spring 22, a generally Y-shaped element 23 with a forked end portion 232, an operation member 24 and a pivot pin 25. The lock body 21 includes a handle hole 211 formed therethrough for passage of the arm of the handle 11, a hole 212 communicated with the handle hole 211, two tab units 213 respectively and rotatably mounting-the pins 231 of the element 23 in the lock body 21, and two pivot holes 214. The pivot pin 25 extends through the hole 241 of the operation member 24 and the pivot holes 214 of the lock body 21 so as to mount the operation member 24 rotatably on the lock body 21. Two holes 26, 27 are formed in the lock body 21 so as to respectively couple with one of the front wheel support rods 12 and one of the rear wheel support rods 13.
As best shown in FIG. 3, the operation member 24 has a limiting barb 242 confining the spring 27 in the space between the operation member 24 and the lock body 21, and a limiting arm 243 biased by the spring 27 to confine the projection 111 of the handle 11 in the space between the limiting barb 242 and the limiting arm 243 when unfolding the stroller frame. When one desires to fold the stroller frame, the limiting barb 242 of the operation member 24 is pressed so as to permit the handle 11 to move relative to the lock body 21.